Piston packing



Aug. 27,1935. E. c. HORTON AL.

FIST-ON PACKING Filed Sept 13, 1935 Erm'zzdjiozian, Anion 'Rqppl;

Patented Aug. 2 7, 1935 UNITED STATES PISTON PACKHNG Erwin C. Horton,

Hamburg, and Anton Rappl,

Buffalo, N. Y., assignors to Trico Products Corporation, Buffalo, N. Y.

Application September 13, 1933, Serial No. 689,258 4 Claims. (01. 309-22) This invention relates to'a piston packing and primarily is designed for the packing of pistons in the vane type of differential pressure or so-called suction-operated windshield cleaner motors.

In the vane type motor of suction-operated -windshield cleaners the piston comprises a pair of cupped leathers arranged edge to edgein opposition to each other, each leather packing memher being clamped between a pair of fiat plates from which the marginal portions of the leather project for contacting the walls of the motor chamber or cylinder. Each half or section of the vane piston comprises the cupped or flanged leather packing clamped between said pair of plates, and the two halves, comprising the piston, are secured to the opposite sides of the rock shaft which is journalled in the motor casing. The shaft as a rule is not packed about its journalled bearings so that atmospheric pressure may leak along the shaft and enter between the halves or sections of the piston thereby tending to hold the marginal. flanges of the same outwardly against the walls of the piston chamber. The vane is also mounted on the shaft so as to extend above and. below the same for effecting a more efficient type of vane motor which will be practically devoid of leakage about the piston from one side to the other.

The thickness of .the leather, the wear, and also the quality thereof determines to some extent the thoroughness with which the leather packings prevent the leakage of atmospheric pressure thereabout to the low pressure side. Also the wear and tear on the piston packing, together with grease and oil collecting thereon when in use, will cause the leather packings to become set or to give up some of their inherent resiliency or yieldability so that the marginalportions will fail to bear evenly against the walls of the piston chamber, thereby resulting in leakage and a consequential inefiiciency in the operation of the windshield cleaner.

In packing assemblies for fluid pressure motors of the positive pressure type, expanders of a rather stiii' resilient metal have been incorporated to hold the leather flanges in contact with the cylinder walls. Obviously, these expander elements create additional friction to be overcome by the fluid pressure, which additional load is undesirable in suction-operated windshield cleaner motors since the available poweris limited. Attempts have been made to weaken the spring pressure of such expanders by serrating the edges thereof thereby providing separate and independent tongues or small fingers which bear at spaced points on the marginal flanges of the leather packings, The serrated portions of such expanders do not provide uniform'pressure on i the leather packings continuously thereabout, and

then too the serrations when of a stiif, resilient the leather and thereby impair its packing qualities. Furthermore, with expanders of a stiff, resilient metal the portions thereof which bear upon the marginal flanges or portions of the cupped leathers are pre-shaped or pre-formed so as tonest within the cupped leathers, necessitating further operation on the expander and resulting in additional expense in the production of the same.

The present invention has for its objects to provide a novel form of expander for the cup leathers of suction-operated windshield cleaner motors, affording light pressure to retain the marginal portions of the leather in constant and uniform contact with the walls of the piston chamber; to provide a packing expander which may be economically and expeditiously produced, and without requiring any pre-formation; to provide a piston construction embodying a packing expander element which may be easily assembled and manufactured; and to provide a resilient meshor foraminous packing expander member provided with non-fraying marginal portions which are free and unsupported for resiliently pressing against the marginal portions of the leather packing.

In the drawing:

Fig. 1 is a vertical lengthwise section of asuc' tion-operated windshield cleaner motor showing a vane type piston, in section, embodying the improved piston packing expander.

Fig. 2 is an enlarged showing of a portion of the mesh expander element.

Fig. 3 is a disassembled view in perspective showing the elements of the improved vane piston and their method of assembly.

Fig. 4 is an enlarged fragmentary showing of the improved piston packing.

Referring more in detail to the accompanying drawing, the numeral I designates the casing of the windshield cleaner motor having a-piston chamber with portions of different radii, the largest chamber portion 2 constituting a pressure application chamber in which the power is applied to the vane andthe smaller chamber 3, formed above the shaft 4, constituting the packing chamber for receiving that portion of the pistonor vane which extends above said shaft to provide an eflicient and substantially leak-proof packing for the shaft and thecasing.

The piston (Figs. 3 and 4) comprises two halves rivet 9, while their inner end portions are secured together by the common fastening member l0 which extends completely through both sections of the piston and the interposed motor ,shaft 4, whereby the piston or vane is firmly flxed to the shaft for movement therewith.

The inner plates 6 of the piston sections are provided with inturned marginal flanges l I which extend away from the composite packing member I and toward the companion plate when the piston is assembled. The marginal portions or flanges l2 of the leather packing extend beyond the margin of the inner and outer body plates 5 and 6 and turn toward each other so that suction obtaining in the chambers 2 and 3 at either side of the piston tends to urge the adjacent flanges l2 outwardly into sealing relation with the inner walls of these'chambers.

The expander members 8 are of mesh or inraminous material to exert suflicient pressure on the packing flanges l2 to hold them out lightly against the walls of the piston chambers 2 and 3. Thus, the expander members are cut' or otherwise formed from extremely thin copper wire mesh in such fashion that the individual wires of the mesh terminate at the marginal edges of the-expander members at an angle to both the lateral and longitudinal axis and thus present a nonfraying edge, that is to say, the mesh is cut on thebias. By cutting the mesh in this way an expander member with a resilient mesh non-fraying marginal portion is provided which extends substantially co-extensive with the terminal edge of the leather packing member without the formation of loose and frayed wires within the interior of the chamber which would interfere with the necessary tight contact between the edges of the piston vane and the interior walls of the topof the chamber or cut or damage the edges of the packing.

The major portion'of the expander member is given reinforcement by the superimposed inner plate 6, the latter being nearly co-extensive with the expander but leaving the marginal flanges 8', constituting the active portion of the expander, projecting about the flanges H and for pressing the edge H! of the packing 1 against the chamber wall I. From Fig. 3 it will'be observed that the active portions or flanges 8' of the expander are continuous and uninterrupted to exert uniform pressure on the packing flanges l2 whereby the latter will be urged into uniform and continuous contact with the inner walls of the piston chamber. It will also be noted from Figs. 3 and 4 that the marginal edges of the expander tor-,- minate just short of the marginal edges of the leather packing and are substantially co-extene sive therewith thereby urging the marginal portions of the leather packing into contact with the inner walls of the piston chamber.

In assembling .each section ofthe piston vane, the inner rigid expander plates areassembled upon the pin l0 passing through shaft 4 and upon pin 9 in such fashion that the marginal flanges I l of the plates 6 extend toward each oth- The flat undistorted expander member B'is placed upon the inner rigid plate 6 and the preformed leather packing member 1 is placed over the mesh expander member and the whole assembled tightly by means of the outer rigid plate 5, the tab member l4 being assemb ed upon the pin 9. Upon placing the piston within the casing, the pre-formed and marginal edges oi the leather packing member are pressed lightly against the inner walls of the chamber by the expander member 8 although the pre=formed packing members are more or less conformable to the shape of the piston chamber.

It will thus be seen from the foregoing description that a packing member is provided in which the edges of the packing are pressed lightly against the chamber walls and wherein a resilient mesh margin is. provided for urging the fabric packing against the chamber walls without danger of scoring the walls from rigid metal projections or from frayed portions of the expander member.

What is claimed is:

1. A piston assembly for fluid pressure motors, comprising a pair of rigid plates flxed intermediate their ends to opposite sides of a motor shaft and extending above and below the same, an angularly.shaped cupped packing for each plate having a plurality of flanges receiving the plate between the flanges and extending across the shaft above and below the same and extending beyond the plate, and an independent resilient mesh expander member interposed between the inner plate and the packing member and extending across the shaft above and below the same and having its marginal edges projecting from beneath the rigid plate and substantially co-extensive with the edges thereof.

2. A piston assembly for windshield cleaner motors of the differential fluid pressure operated type, comprising a cupped packing, an inner rigid plate, an outer rigid plate, a flexible expander member of foraminous construction independent of said packing interposed between one of said rigid plates and said packing, said flexible member having a marginal portion extending beyond the body lines of the last mentioned rigid plate and normally tending to return toward the body plane of said expander member and said marginal portion being shaped under tension by the flanges of said cupped packing when held in their working position.

3. A piston assembly for fluid pressure motors,'

extending across the shaft above and below the same and extending beyond the plates, and an expander member having resilient mesh marginal portions interposed between and secured against relative creeping to said rigid plate and packing and extending across the shaft above and below the same, said member being secured within the cupped packing by its rigid plate and having its continuous mesh marginal portions projecting from beneath the rigid plate and terminating just short of the edges of the packing member and at one side thereof 4. A cup packing comprising a cupped packing member and a resilient backing member, said backing member having a resilient mesh marginal portion for nesting in the cup packing, said marginal portion being independent of the packing.

ERWIN C. HORTON. ANTON RAPPL. 

